Recombinant DNA technology has greatly increased our ability to study gene structure and function. This technology can now be applied to monoclonal antibody (Mab) production. Monoclonal antibodies facilitate biochemical analysis of proteins by their highly-specific recognition of a single epitope. Conventional methods for generating Mabs are not capable of efficiently surveying the induced antibody response to a given antigen. For example, an individual animal has 5-10,000 different B-cell clones, each capable of producing unique antibodies to an antigen. However, with the current cell-fusion technique, only a few hundred different antibodies can be produced. Recombinant DNA technology allows the immunoglobin variable region genes to be amplified, which provides for the generation of a large CDNA library using the bacteriophage lambda-immuno-zap expression vectors. This library is much easier to access than hybridomas produced from cell fusion. Screening is also greatly enhanced, considering immunoglobin gene products of at least 50,000 clones or 1-10,000,000 antibodies can be readily examined in one day, compared to screening hybridomas, which is labor-intensive, time-consuming and expensive. Once produced, these expression vectors can be transfected into mammalian cells or used for making transgenic mice. Currently, we have cloned the heavy and light chain genes of the pan-ets (T-7) antibody directed against the human ETS2 oncoprotein. The light chain has been success-fully inserted into the lambda-Lcl expression vector and a library has been constructed. Work continues with progress to construct the heavy chain library.